1. Field of the Invention
Certain heterocyclic ureas are useful in protecting plants from the deleterious effects of atmospheric ozone. Ozone is a common air pollutant around urban areas which has been found to damage crop plants, ornamental plants and shade and forest trees. Polluted air is estimated to cost farmers a half-billion dollars a year. Even air that contains a level or ozone below that common to urban areas reduces yields of many crops.